The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jan. 11, 1994
Filed:
Apr. 11, 1991
John L Murphy, San Francisco, CA (US);
Mark J Rich, Menlo Park, CA (US);
USA Digital Radio, Los Angeles, CA (US);
Abstract
A radio broadcasting system is provided for transmitting and receiving through free space a fully coherent multicarrier modulated digital signal which is especially adapted to be resistive to multipath degradation. The multicarrier modulated signal is a synthesized vector-modulated signal which is a quadrature phase shift keyed (QPSK) modulated set of synthesized carriers phase coherent with each other and each occupying a spectrum replicated multiple times within a bandwidth with no more than two bits per vector. An efficient channel coding consisting of large block size, high efficiency block coding, such as BCH 255, 239 code, is employed in connection with time interleaving of bits to mitigate the effects of frequency selective multipath and broadband multipath. The broadcast system is designed to be used in support of compressed digital audio programming material. In a demodulation process according to the invention, a demodulator is operative to phase lock to a reconstructed or otherwise coherent pilot tone or equivalent clock, to coherently demodulate the digital signal, to deinterleave, to decode the block encoded signal and to format the recovered data stream for source decoding.